The present invention relates to apparatus and methods for hydraulically mining mineral deposits, and more particularly, to a modular hydraulic mining tool and improved method of hydraulically mining high viscosity crude oil mineral formations such as tar sands and oil shale.
In recent years, hydraulic mining techniques have been developed which permit the recovery of subterranean mineral deposits by use of a high velocity liquid stream being discharged directly into the mineral deposit to dislodge the minerals from the surrounding mineral bed. The discharged liquid mixes with the freed mineral particles and forms a resultant aqueous slurry which may be pumped as by way of a hydraulic jet pump to ground surface for subsequent processing by conventional or unconventional separation systems.
To date, the majority of the prior art hydraulic mining tool apparatus have been effectively utilized to primarily recover minerals such as uranium ore or coal, which due to their generally uniform noncohesive structure, rapidly dislodge from the mineral deposit, readily migrate within the aqueous slurry, and typically transport without conglomeration, upward within the jet pump of the mining tool. However, in the recovery of viscous crude oil minerals, such as tar sands and oil shale, peculiar mining problems exist which to a great extent has rendered the heretofore hydraulic mining systems ineffective and commercially impracticable.
These peculiar mining problems are a result of the basic composition of viscous crude oil mineral formations which typically are of a non-uniform nature, varying significantly between different mineral bed sites as well as throughout the elevation of the same mineral bed site. With specific reference to tar sand mineral formations, it has been found that due to the high cohesive and adhesive properties of the bitumen constituent contained therein, the individual tar sand mineral particles often are strongly held or bound in the mineral formation and are difficult to hydraulically dislodge from the mineral bed. Similarly, when freed from the formation, such bound tar sand particles often are in the form of a gum or clay-like mass which does not readily migrate within the aqueous slurry and is highly susceptible to becoming lodged within and obstructing the internal components of the hydraulic mining tool.
In addition, due to the highly non-uniform nature of tar sand and oil shale mineral formations, the bore hole in which the mining tool is inserted, is highly susceptible to cave-in situations wherein the mineral formation falls in and around the drill string during the mining operation. These cave-in situations result in substantial frictional forces being developed in and around the mining tool and drill string which generate substantial torque on the mining tool during rotation. As such, extremely high tortional strength requirements are necessitated in tar sand and oil shale mining applications which are not typically encountered in uranium or coal formation mining.
Further, in contrast to uniform, light cohesive and adhesive mineral formations, the hydraulic mining efficiency rate in tar sand and oil shale mineral formations i.e., the amount of the mined mineral being transported to ground surface per unit of time, is typically sporadic due to the varying consistency of the mineral formation. In this regard, the majority of the prior art hydraulic mining tool systems have failed to include any means for adjusting the operation of the tool to compensate for the variances in the consistency of the formation and typically have relied solely upon natural gravity force migration of the aqueous slurry within the formation and the suction developed by the hydraulic jet pump to introduce the mined minerals into the mining tool.
Thus, there exists a substantial need in the art for a hydraulic mining tool apparatus which is specifically adapted to withstand the high tortional forces, accomodate the non-uniform, cohesive and adhesive properties, and compensate for the varying formation consistency encountered in viscous crude oil mineral formations.